Heat exchanger assembly having at least one multi-pass heat exchanger and method for operating a heat exchanger assembly

ABSTRACT

The invention relates to a heat exchanger assembly with at least one multi-pass heat exchanger, comprising a first distributor ( 1 ) with a first connection part ( 1   a ) for connecting to a fluid line ( 9 ), a second distributor ( 2 ) with a second connection part ( 2   a ) for connecting to a fluid line ( 9 ), and at least one first deflection distributor ( 4 ), as well as a plurality of tube lines ( 5 ) through which a fluid, in particular water, can flow, wherein the first distributor ( 1 ) and the second distributor ( 2 ) are arranged at one end (A) of the heat exchanger assembly, the deflection distributor ( 4 ) is arranged at the opposite end (B) and the tube lines ( 5 ) extend from the one end (A) to the opposite end (B), and wherein the first connection part (1 a ) is arranged at a lowest point (T) or at least near to the lowest point (T) of the first distributor ( 1 ) and the second connection piece ( 2 a) is arranged at a lowest point (T) or at least near to the lowest point (T) of the second distributor ( 2 ). In order to allow for the heat exchanger assembly to be quickly filled with the fluid and quickly emptied, a third connection part ( 3 ) is arranged on the first distributor ( 1 ) and/or on the second distributor ( 2 ) at a highest point (H) or at least near to the highest point (H) of the respective distributor ( 1  or  2 ), and at least one ventilation opening ( 10 ) is provided at a highest point (T) or at least near to the highest point (T) of the deflection distributor ( 4 ) for pressure equalisation with the environment.

The invention relates to a heat exchanger assembly having at least onemulti-pass heat exchanger, which comprises a first and a seconddistributor, each having a connection piece for connecting to a fluidline, as well as at least one first deflection distributor and aplurality of pipelines, wherein a fluid, in particular water, can flowthrough the pipelines. The invention further relates to a method foroperating a heat exchanger assembly of this kind.

Heat exchanger assemblies of this kind having at least one multi-passheat exchanger can be used, for example, as recoolers in cooling systemsfor cooling a fluid that is used as the heat transfer medium in thecooling system. The recooler is generally placed outside a device to becooled, for example outside a building. If water is used as the heattransfer medium, there is therefore a risk of the heat transfer mediumfreezing in the event of frost at the location where the recooler isinstalled.

Cooling systems having heat exchanger assemblies that allow the recoolerto be emptied in an anti-freeze mode are therefore known from the priorart. For example, from WO2018/184908 A1 a cooling system with circulatedwater as heat transfer medium is known, which contains a recooler and awater tank, wherein the recooler comprises an inlet collector and anoutlet collector at a first end region and a deflection collector havinga first and a second branch arranged in a V-shape relative to oneanother at its second end region opposite the first end region. Thefirst branch and the second branch of the deflection collector areconnected to each other via a connecting branch arranged at their upperend, wherein a vent opening is arranged in the connecting branch. Afirst pipe arrangement which rises in a flow direction extends betweenthe inlet collector and the first branch of the deflection collector,and a second pipe arrangement which falls in the flow direction extendsbetween the second branch of the deflection collector and the outletcollector. The non-pressurized water tank is connected to an inlet atthe inlet collector and to an outlet at the outlet collector such thatthe cooling water stored in the water tank can be conducted through therecooler in a closed circuit. For ventilation, the water tank isconnected to the recooler via a vent line that flows into the ventopening on the connecting branch of the deflection collector. Therecooler thus formed has two single-pass registers connected in serieshaving a first tube assembly formed as a supply line connecting theinlet collector to the deflection collector and forming a firstsingle-pass register, and a second tube assembly forming a secondsingle-pass register which runs between the deflection collector and theoutlet collector to connect the deflection collector to the outletcollector. In a recoiling mode, the water conducted through the pipearrangements is cooled by heat exchange with drawn-in ambient air. Forthis purpose, the cooling water stored in the water tank is conductedthrough the recooler by means of a circulating pump. To empty therecooler if there is a risk of frost, this known cooling system providesfor the circulating pump to be switched off. When the circulating pumpis switched off, the recooler empties automatically as a result of theconstant ventilation of the deflection collector in conjunction with thegradient of the two pipe arrangements of the two single-pass registers.

However, heat exchanger assemblies having one or more single-passregisters connected in series (single-pass heat exchangers) have a lowercooling efficiency compared with multi-pass systems, in which thecooling medium passes through the heat exchanger(s) several times. Heatexchanger assemblies having multi-pass registers are thereforefrequently used to improve the cooling efficiency and to increase thecooling capacity. This is especially necessary if a cooling capacity ofbetween 100 and 1500 kW is to be achieved.

A cooling assembly having a two-pass register is known, for example,from WO 90/15299-A. The cooling water used therein as the heat transfermedium flows through a heat exchanger of the cooling system twice(2-pass heat exchanger). For this purpose, a heat exchanger is providedhaving an inlet collector arranged at one end of the heat exchanger andan outlet collector as well as a deflection collector arranged at theopposite end, wherein pipelines formed as supply lines extend betweenthe inlet collector and the deflection collector and pipelines formed asrecirculating lines extend between the deflection collector and theoutlet collector. In a recooling mode, the cooling water is firstconducted through the supply lines in a first pass and through therecirculating lines in a second pass. As the cooling water passesthrough the pipelines of the two-pass heat exchanger, heat exchangetakes place with an air stream of ambient air drawn in by a fan andconducted through the two-pass heat exchanger, in order to cool thecooling water.

When using multi-pass heat exchangers in areas subject to frost, thereis a risk that the multi-pass heat exchanger cannot be emptied quicklyenough or completely enough to prevent the heat transfer medium(especially cooling water) from freezing. Particularly when thetemperature of the heat transfer medium located in the multi-pass heatexchanger drops very quickly as a result of a rapid decrease in theambient temperature or a strong wind influence on the heat exchanger, itmust be ensured, even when using multi-pass heat exchangers, that theheat exchanger can be completely emptied within a very short period oftime in order to prevent the heat transfer medium from freezing.However, rapid emptying of a multi-pass heat exchanger is difficult dueto the long pipelines through which the heat transfer medium flowsmultiple times and the resulting long transport paths of the heattransfer medium through the pipelines of the multi-pass heat exchanger.The length of the pipelines (of a supply and recirculating line) can bebetween 3 and 15 m. For the same reason, rapid refilling of a multi-passheat exchanger when resuming recooling mode once the risk of frost haspassed is also difficult.

Based on this, it is the object of the invention to demonstrate a heatexchanger assembly having at least one multi-pass heat exchanger, whichhas a high cooling capacity with the highest possible efficiency and canbe emptied as quickly and completely as possible when there is a risk offrost and which can also be refilled with a heat transfer medium asquickly as possible for a resumption of recooling mode after the risk offrost has ended.

These objects are achieved according to the invention by having a heatexchanger assembly with the features of claim 1 and by a method with thefeatures of claim 20. Further contributing to achieving the object is acooling system according to claim 19, in which a heat exchanger assemblyaccording to the invention is used as a recooler for cooling a fluidused as a heat transfer medium.

The heat exchanger assembly according to the invention comprises atleast one multi-pass heat exchanger, in particular a two-pass or afour-pass heat exchanger, wherein the or each heat exchanger comprises afirst and a second distributor each having a connection piece forconnecting to a fluid line, as well as at least one first deflectiondistributor and a plurality of pipelines through which a fluid, inparticular water, used as heat transfer medium can flow. Here, the firstand second distributors distributor are arranged at one end of the heatexchanger assembly and the first deflection distributor is arranged atthe opposite end of the heat exchanger assembly, and the pipelinesextend from one end to the opposite end in order to connect the firstand second distributors to one of the deflection distributors. Here, afirst connection piece is arranged at a lowest point or at least nearthe lowest point of the first distributor, and a second connection pieceis arranged at a lowest point or at least near the lowest point of thesecond distributor. Furthermore, a third connection piece is arranged onthe second distributor at a highest point or at least near the highestpoint of the second distributor.

Where reference is made to a highest point of a distributor, thegeodetically highest point of the respective distributor is what ismeant. Where reference is made to a lowest point, the geodeticallylowest point of the respective device (distributor) is meant in eachcase, in particular the lowest point seen in relation to the verticaldirection. This also includes a point that is at least in the vicinityof the geodetically highest or geodetically lowest point.

By designing a heat exchanger assembly according to the invention havingat least one multi-pass heat exchanger, both a fast emptying and a fastfilling of the multi-pass heat exchanger(s) with the fluid used as heattransfer medium can be achieved, in that, in the event of a risk offrost in an emptying operation, due to an inclination of the pipelinesto the horizontal, the fluid can flow off by gravity simultaneously fromall of the pipelines into the first and the second distributor as wellas into the third deflection distributor and from there in each case viaa connection piece arranged at the lowest point of the first and thesecond distributor and of the third deflection distributor (first orsecond connection piece) into a fluid line connected to the connectionpieces. In a corresponding manner, the fluid can be introduced veryquickly against gravity from the first and second distributorssimultaneously into all pipelines of the multi-pass heat exchanger in afilling mode. This significantly reduces the emptying or filling timewhen emptying or filling the heat exchanger, due to the fact that thefluid is not introduced into the multi-pass heat exchanger(s) accordingto the flow paths during recooling mode of the heat exchanger assembly,but can flow simultaneously into or out of all pipelines of themulti-pass heat exchanger via the first and second distributors.

Rapid outflow of the fluid out of the pipelines of the multi-pass heatexchanger in emptying mode is assisted by a slope of the pipelinesrelative to the horizontal plane. The pipelines, which are convenientlyparallel to one another, preferably include an angle of between 0.5° and5° with the horizontal, and more preferably an angle of between 2° and4°, in particular 3°.

The multi-pass heat exchanger can, for example, be a 2-pass heatexchanger in which the fluid flows twice through the pipelines of theheat exchanger and is thereby in heat exchange with cooling air, whichis conveniently drawn in from the environment by one or more fans andconducted through the heat exchanger.

The pipelines of each multi-pass heat exchanger are thereby divided intoa first group of pipelines and a second group of pipelines, wherein thefirst group of pipelines serves as supply lines and the second group ofpipelines serves as recirculating lines. In recooling mode, for example,the fluid can be introduced into the first distributor via the firstconnection piece, which is formed as an inlet distributor, and the fluidflows through the supply lines (first group of pipelines) of the 2-passheat exchanger in a first pass to the first deflection distributor andis deflected from there into the return lines (second group ofpipelines), so that the fluid can then flow back in a second pass in therecirculating lines to the second distributor (outlet distributor). Thefluid exits the two-pass heat exchanger via the third connection piecearranged at the highest point of the second distributor. In the process,the two distributors (first and second distributors) are alsointerchangeable with one another, i.e., it is possible for the fluidfirst to flow into the second distributor, which is formed as an inletdistributor, and to flow out of the first distributor, which is formedas an outlet distributor.

The multi-pass heat exchanger can also be a 4-pass heat exchanger, inwhich the fluid flows four times through the pipelines of the heatexchanger while being in heat exchange with the cooling air. In a 4-passheat exchanger, in addition to the first and second distributors and thefirst deflection distributor, a second and a third deflectiondistributor are provided, wherein the first and second distributors andthe third deflection distributor are located at one end of the heatexchanger assembly and the first and second deflection distributors arelocated at the opposite end of the heat exchanger assembly and thepipelines extend from the one end to the opposite end to connect thefirst and second distributor to one of the deflection distributors.Here, a connection piece is again arranged at a lowest point or at leastnear the lowest point of the first distributor and the seconddistributor (first and second connection pieces), and on the seconddistributor a third connection piece is again arranged at a highestpoint or at least near the highest point of the second distributor. Afourth connection piece is conveniently arranged on the third deflectiondistributor at a lowest point or at least near the lowest point of thethird deflection distributor.

In the recooling mode of the 4-pass heat exchanger, for example, thefluid can be introduced into the first distributor via the firstconnection piece, which is formed as an inlet distributor, and the fluidflows through the supply lines (first group of pipelines) of the 4-passheat exchanger in a first pass to the first deflection distributor andis deflected from there into the recirculating lines (second group ofpipelines) so that the fluid then flows back in a second pass in therecirculating lines to the third deflection distributor at the first endof the heat exchanger assembly and is deflected there from the thirddeflection distributor back into pipelines of the first group (supplylines) and flows in a third pass to the second deflection distributorand is deflected there again into pipelines of the second group(recirculating lines) and finally flows back in a fourth pass to thesecond distributor (outlet distributor). The fluid exits the multi-passheat exchanger via the third connection piece arranged at the highestpoint of the second distributor. In the process, the two distributors(first and second distributors) are also interchangeable with oneanother, i.e., it is possible for the fluid first to flow into thesecond distributor, which is formed as an inlet distributor, and to flowout of the first distributor, which is formed as an outlet distributor.

To ensure that the multi-pass heat exchanger is completely filled withfluid at all times during filling and recooling mode (which can improveefficiency), it is preferable for both the 2-pass and 4-pass heatexchangers that the fluid enters the heat exchanger through the firstconnection piece (at the lowest point of the first distributor) andexits the heat exchanger at the third connection piece (at the highestpoint of the second distributor). Preferably, the distributor (seconddistributor), which contains the third connection piece at its highestpoint, is arranged in the heat exchanger assembly on the outside, i.e.,towards the inflow surface.

For pressure equalization with the environment (i.e., with theatmospheric air pressure), a vent opening is arranged at least on one ofthe deflection distributors, in particular on the first and—in the caseof the 4-pass heat exchanger—on the second deflection distributor. Thevent opening is conveniently located at or near the highest point of therespective deflection distributor. Complete ventilation of thedeflection distributors can thereby be ensured.

The distributors, i.e., the first and second distributors and eachdeflection distributor, can each be formed as tubular manifolds. Thetubes of the distributors can be arranged vertical with theirlongitudinal axis or inclined obliquely to the vertical.

A high heat exchange efficiency and a compact design of the heatexchanger assembly can be achieved if the heat exchanger assemblycontains two multi-pass heat exchangers arranged opposite each other,the two multi-pass heat exchangers being inclined obliquely to thevertical and arranged in a V-shape relative to one another.Corresponding to this obliquely assembly of the heat exchangers, thetubular distributors (first distributor and second distributor as wellas the deflection distributors) are also oblique to the vertical.

A particularly compact design can be achieved when the first and seconddeflection distributors are contained in a common header tube having apartition disposed therein, wherein the partition divides the commonheader tube into an inflow region forming the first distributor and anoutflow region forming the second distributor. In a correspondingmanner, in the case of the 4-pass heat exchanger, the first and seconddeflection distributors, which are each arranged adjacent to one anotherat the other end of the heat exchanger assembly, can also be arranged ina common header tube having a partition wall, the partition walldividing the header tube into at least two regions, a first regionforming the first deflection distributor and a second region forming thesecond deflection distributor.

In a corresponding manner, in the case of the 4-pass heat exchanger, thefirst distributor, the second distributor and the third deflectiondistributor, which are each arranged adjacent to one another at one endof the heat exchanger assembly, can also be arranged in a common headertube, the header tube in turn containing a separating element whichdivides the header tube at least into an inflow region (which forms thefirst distributor), an outflow region (which forms the seconddistributor) and a deflection area (which forms the third deflectiondistributor). The first, second, third and fourth connection pieces arearranged in the common header tube, the first connection piece beingarranged in the inflow region at a lowest point of the common headertube, the second connection piece being arranged in the outflow regionat a highest point of the common header tube, the third connection piecebeing arranged in the outflow region at a lowest point of the commonheader tube, and the fourth connection piece being arranged at a lowestpoint of the deflection area.

In order to be able to open or close the first and second connectionpieces and, if applicable, the fourth connection piece provided in the4-pass heat exchanger, which are each arranged at a lowest point of therespective distributor (first distributor and second distributor, thirddeflection distributor if applicable), depending on the operating modeof the heat exchanger assembly, a controllable valve is preferablyassociated with each of these connection pieces. In particular, thecontrollable valve can be arranged in the respective connection piece(first, second or fourth connection piece). The controllable valves canbe actuated, for example, hydraulically, pneumatically, or electrically.

In a convenient embodiment of the heat exchanger assembly, the first andsecond distributors and the third deflection distributor are arranged ata front-side end of the heat exchanger assembly, and the first andsecond deflection distributors are arranged at the opposite, rear faceof the heat exchanger assembly. In the case of the 4-pass heatexchanger, the third deflection distributor is arranged on the frontface adjacent to the first and second distributors and the seconddeflection distributor is arranged on the rear face adjacent to thefirst deflection distributor. As a result, it is possible to ensure acompact design of the heat exchanger assembly and dimensions thatsatisfy the requirements in terms of cooling capacity.

The heat exchanger assembly according to the invention can be operatedboth in the 2-pass and in the 4-pass version in various operating modes,in particular in a recooling mode, an emptying mode in case of risk offrost, a filling mode for initial filling of the heat exchanger assemblyor for refilling after the risk of frost has ended, and in a standbymode after the heat exchanger assembly has been emptied in case of riskof frost or if frost persists. A control device for controlling the heatexchanger assembly is provided for switching the heat exchanger assemblyfrom one operating mode into another operating mode. The control of theheat exchanger assembly, and in particular the setting of a suitableoperating mode, is carried out as a function of ambient parameters, suchas the outside temperature and the wind speed at the installation siteof the heat exchanger assembly. For detecting the ambient parameters,sensors, in particular a thermometer for detecting the outsidetemperature and an anemometer for detecting the wind speed, areconveniently provided and coupled to the control device. The measuredvalues of the ambient parameters, as detected by the sensors, aresupplied to the control device. In addition to the ambient parameterssuch as outside temperature and wind speed, the inlet temperature of thefluid as it enters the heat exchanger assembly is conveniently detectedvia additional sensors, in particular thermometers. Furthermore, thevolume flow rate of the fluid stream flowing into the heat exchangerassembly or flowing out of the heat exchanger assembly can be measuredvia pressure or flow sensors and be transferred to the control device.The control device calculates a predicted outlet temperature of thefluid as it exits the heat exchanger assembly based on the suppliedmeasured values, in particular taking into account the outsidetemperature and the inlet temperature of the fluid. If the calculatedoutput temperature is greater than or equal to a predetermined limitvalue, the control device switches the operation of the heat exchangerassembly from recooling mode into emptying mode. At low outsidetemperatures below the freezing point of the fluid (which is preferablywater), a risk of the fluid freezing can be detected from the calculatedoutput temperature of the fluid as it exits the heat exchanger assembly.In such a situation, to prevent the fluid from freezing in the pipelinesor the distributors of the heat the distributors of the heat exchangerassembly, the control device switches as quickly as possible to emptyingmode, in which the fluid in the pipelines can flow simultaneously out ofall of the pipelines into the first and second distributors and thethird deflection distributor, which may be present (in the case of the4-pass heat exchanger), and from there through the connection piecesarranged in each case at the lowest point of these distributors (first,second and fourth connection piece) into a fluid line in connection withthese connection pieces from the area at risk of frost.

These and other features and advantages of the invention will beapparent from the exemplary embodiment described in more detail belowwith reference to the accompanying drawings. In the drawings:

FIG. 1: is a representation of a first exemplary embodiment of a heatexchanger assembly according to the invention having two 4-pass heatexchangers arranged in a V-shape relative to one another, in a view of afront face of the heat exchanger assembly;

FIG. 2: is a side view of the 4-pass heat exchanger assembly of FIG. 1;

FIG. 3: is a schematic representation of various operating modes of theheat exchanger assembly of FIGS. 1 and 2, where FIG. 3a shows arecooling mode, FIG. 3b shows a filling mode, and FIG. 3c shows anemptying mode of a multi-pass heat exchanger of the heat exchangerassembly;

FIG. 4: is a representation of a second exemplary embodiment of a heatexchanger assembly according to the invention having two 2-pass heatexchangers arranged in a V-shape relative to one another, in a view of afront face of the heat exchanger assembly;

FIG. 5: is a view towards the rear face of the 2-pass heat exchangerassembly of FIG. 4;

FIG. 6: is an overview of the second exemplary embodiment of a heatexchanger assembly according to the invention having two 2-pass heatexchangers arranged in a V-shape relative to one another in a view ofthe front face of the heat exchanger assembly (FIG. 6a ), of the rearface of the 2-pass heat exchanger assembly (FIG. 6b ) and in a side view(FIG. 6c );

FIG. 7: is a schematic representation of different operating modes ofthe 2-pass heat exchanger assembly of FIG. 6, where FIG. 7a shows arecooling mode, FIG. 7b shows a filling mode and FIG. 7c shows anemptying mode of the 2-pass heat exchanger;

FIG. 8: shows representations of the various operating modes of the2-pass heat exchanger assembly of FIG. 7 by means of sectional drawingsof the 2-pass heat exchanger through a horizontal plane, where FIG. 7ashows the recooling mode, FIG. 7b shows the filling mode, and FIG. 7cshows the emptying mode of the 2-pass heat exchanger;

FIG. 9: is a schematic representation of a cooling system containing aheat exchanger assembly according to the invention having two opposite2-pass heat exchangers, where FIG. 9a shows the entire cooling systemand the heat exchanger assembly used therein both in a view of the frontface and in a side view and FIG. 9b shows a detailed view from FIG. 9ain the area of the heat exchanger assembly;

FIG. 10: is a schematic representation of different operating modes ofthe heat exchanger assembly of the cooling system of FIG. 9, where FIG.10a shows the heat exchanger assembly in recooling mode, FIG. 10b showsthe heat exchanger assembly in emptying mode, and FIG. 10c shows theheat exchanger assembly in filling mode;

FIG. 11: is a schematic representation of another exemplary embodimentof a cooling system having a combination of two heat exchangerassemblies according to the invention;

FIG. 12: is a schematic representation of possible operating modes ofthe combination of heat exchanger assemblies from FIG. 11.

FIGS. 1 and 2 show an exemplary embodiment of a heat exchanger assemblyaccording to the invention, which can be used as a recooler R forcooling a fluid used as a heat transfer medium in a cooling system. Inparticular, water can be used as the heat transfer medium. In thefollowing, the term water refers to the fluid used as the heat transfermedium, wherein another fluid can also be used as the heat transfermedium instead of water.

The heat exchanger assembly shown in FIGS. 1 and 2 includes twofour-pass heat exchangers, which contain opposing planar heat exchangersextending obliquely to the vertical. As can be seen from the view ofFIG. 1, the two heat exchangers are arranged in a V-shape relative toone another. The structure of the heat exchanger arranged on theright-hand side of FIG. 1 is explained below. The opposite heatexchanger arranged on the left-hand side of the heat exchanger assemblyis constructed similarly. The two heat exchangers are attached to ahousing 21 of the heat exchanger assembly. Each heat exchanger comprisesa first distributor 1, formed as an inlet distributor, a seconddistributor 2, formed as an outlet distributor, as well as a firstdeflection distributor 4, a second deflection distributor 6 and a thirddeflection distributor 8, and a plurality of pipelines 5. The firstdistributor 1, the second distributor 2 and the third deflectiondistributor 8 are arranged at the front face end A of the heat exchangerassembly. The first and second deflection distributors 4, 6 are eacharranged at the opposite end B of the heat exchanger assembly, i.e., atthe rear face. The pipelines 5 extend in a longitudinal direction L ofthe heat exchanger assembly from one end A to the opposite end B. Thepipelines 5 are thereby divided into a first group of pipelines 5 a anda second group of pipelines 5 b, wherein the first group of pipelines 5a serve as supply lines and the second group of pipelines 5 b serve asrecirculating lines. Some of the pipelines 5 of the first group ofpipelines 5 a (supply lines) connect the first distributor 1 (inletdistributor) to the first deflection distributor 4, and some of thepipelines 5 of the second group of pipelines 5 b (return lines) connectthe first deflection distributor 4 to the third deflection distributor8. Some of the pipelines of the first group of pipelines 5 a (supplylines) in turn connect the third deflection distributor 8 to the seconddeflection distributor 6, and some of the pipelines of the second groupof pipelines 5 b (return lines) in turn connect the second deflectiondistributor 6 to the second distributor 2 (outlet distributor), as shownin FIG. 3. The pipelines 5 of the supply and recirculating lines run atleast essentially parallel to each other and are slightly inclined tothe horizontal, as can be seen in FIG. 2. The inclination angle of thepipelines 5 to the horizontal is preferably between 0.5° and 5°,particularly preferably between 2′ and 4°, and in a preferred exemplaryembodiment the angle between the pipelines and the horizontal plane is3°.

A first connection piece 1 a is arranged on the first distributor 1(inlet distributor) at a lowest point T of this distributor 1. A secondconnection piece 2 a is also arranged at a corresponding location, i.e.,at a lowest point T, on the second distributor 2 (outlet distributor).On the second distributor 2 (outlet distributor), an additionalconnection piece, referred to as the third connection piece 3, isarranged at a highest point H. A connection piece 7, which is referredto as the fourth connection piece, is likewise arranged at the lowestpoint T of the third deflection distributor 8.

The deflection distributors (first and second deflection distributors 4,6) arranged at the opposite end B of the heat exchanger assembly eachhave a vent opening 10 at a highest point H, as shown in FIG. 2. Thevent opening 10 is conveniently arranged at the upper end of thedeflection distributors 4, 6, which are formed as tubular manifolds. Theopposite lower end of the tubular deflection distributors 4, 6 isclosed. Conveniently, a valve 11 is arranged in each vent opening 10,with which the vent opening 10 can be opened or closed. However, the useof a valve in the vent openings 10 can also be omitted.

A controllable valve V for opening and closing each connection piece 3,7 is inserted at least in the second connection piece 2 a, which isarranged at the lower end of the second distributor 2 (outletdistributor), and in the fourth connection piece 7, which is arranged atthe lower end of the third deflection distributor 8 (FIG. 2). Therespective valve V can alternatively be placed at another location,e.g., in a fluid line connected to the respective connection piece 3, 7.The valves V can be controlled independently of one another in order toopen or close the (lower) connection pieces 3 and 7 independently of oneanother.

FIG. 3 schematically shows different operating modes of the heatexchanger assembly. In the retooling mode shown in FIG. 3a , forexample, water is conducted through the pipelines 5 (supply lines 5 aand recirculating lines 5 b) of the heat exchanger assembly as the heattransfer medium. At the same time, (cold) ambient air is sucked in fromthe environment by at least one fan 12 arranged on the upper side of theheat exchanger assembly, as shown in FIGS. 1 and 2, and conductedthrough the heat exchangers of the heat exchanger assembly to perform aheat exchange between the heat transfer medium (water) conducted throughthe pipelines 5 and the drawn-in air. To increase the heat transferefficiency, fins 22 are attached to the pipelines 5 (FIG. 3) in order toincrease the effective heat transfer area. In the exemplary embodimentshown, accordingly the heat exchangers are finned tube or fin-tube heatexchangers. Instead of conventional finned tube or fin-tube heatexchangers, micro-channel heat exchangers may also be used in the heatexchanger assembly according to the invention.

In the recooling mode shown schematically in FIG. 3a , the fluid used asthe heat transfer medium is introduced via the first connection piece 1a into the first distributor 1 (inlet distributor) and from there isconducted through a part of the pipelines 5 of the first group ofpipelines 5 a (supply lines) to the first deflection distributor 4 anddeflected therein into a part of the pipelines of the second group ofpipelines 5 a (return lines). The fluid flows through the recirculatinglines to the third deflection distributor 8, where it is deflected againinto part of the pipelines 5 of the first group of pipelines 5 a (supplylines). The fluid flows in the supply lines to the second deflectiondistributor 6 and is deflected therein again into a part of thepipelines of the second group of pipelines 5 a (recirculating lines) andfinally flows into the second distributor 2 (outlet distributor). Thefluid is withdrawn by the outlet distributor 2 through the thirdconnection piece 3 arranged at the top end of the outlet distributor 2and directed as a cooling medium into a cooling-medium reservoir (tankB) or directly to a consumer to be cooled, via a fluid line 9 connectedto the third connection piece 3.

In the recooling mode according to FIG. 3a , the connection pieces 2 a,7 (second and fourth connection pieces) are dosed by the respectivevalve V arranged therein.

FIG. 3b is a schematic view of the heat exchanger assembly in a fillingmode, in which the heat exchangers can either be filled for the firsttime or can be refilled with the fluid after emptying. In filling mode,the lower connection pieces 2 a and 7 (second and fourth connectionpieces), which are arranged at the lower end of the second distributor 2and of the third deflection distributor 8, respectively, are open. As aresult, the fluid can be simultaneously filled into the first and seconddistributors 1, 2 and the third deflection distributor 8 via theconnection pieces 1 a, 2 a and 7 arranged at the lower end of each ofthe two distributors 1, 2 and the third deflection distributor 8. Thefluid subsequently flows, as shown in FIG. 3b , simultaneously throughall of the pipelines 5 (i.e., through both the supply lines 5 a and therecirculating lines 5 b) in the same direction of flow from the one endA of the heat exchanger assembly to the opposite end B. Due to theinclination of the pipelines 5 towards the front end A, the fluid in thepipelines 5 thereby flows upwards against gravity in the direction ofthe deflection distributors 4, 6 arranged at the rear face end B. Theair present in the first and second deflection distributors 4, 6 isforced out through the vent openings 10 at the upper end of these twodeflection distributors 4, 6, whereby the two deflection distributors 4,6 are vented. In order to prevent the fluid from escaping from the ventopenings 10 when the heat exchangers are completely filled with thefilled fluid, a self closing valve 11 is conveniently arranged in thevent openings 10. The valve 11 automatically closes the vent opening 10as soon as an internal pressure arises in the valve due to the incomingfluid.

To determine when the heat exchanger assembly is completely filled withfluid, the hydrostatic pressure of the fluid in the heat exchangerassembly is detected by means of a pressure sensor (P). Once thehydrostatic pressure detected by the pressure sensor (F) exceeds apredetermined pressure limit value, the heat exchanger assembly isswitched from filling mode to recooling mode. Alternatively, the controldevice S of the heat exchanger assembly can also calculate an expectedfilling time from the parameters of said assembly, and the filling modecan be terminated as soon as the calculated filling time has elapsedwhile filling the heat exchanger assembly with the fluid.

Conversely, analogously to the filling of the heat exchanger assemblywith the fluid, the heat exchanger assembly can also be rapidly emptiedby opening the valves V in or on the second connection piece 2 a and onthe fourth connection piece 7. FIG. 3c shows an emptying mode of theheat exchanger assembly in which, with open valves V in the secondconnection piece 2 a and the fourth connection piece 7, the fluid canflow simultaneously from all of the pipelines 5 (i.e., from both thesupply lines 5 a and the recirculating lines 5 b) by gravity and in thesame flow direction along the incline of the pipelines 5 from the rearend B to the front end A into the first and second distributors 1, 2 andinto the third deflection distributor 8. The flow of the fluid isthereby facilitated on the one hand by the inclination of the pipelines5 towards the front end A and on the other hand by a ventilation of thefirst and the second deflection distributors 4, 6 via the vent openings10. For the ventilation of the first and the second deflectiondistributors 4, 6, the valve 11 in the vent openings 10 is opened sothat ambient air can flow through the vent openings 10 into thedeflection distributors 4, 6. Finally, the fluid can flow out throughthe lower connection pieces 1 a, 2 a and 7(first, second and thirdconnection pieces) into a fluid line (not shown here) connected to saidconnection pieces 1 a, 2 a and 7.

The design of the heat exchangers according to the invention allows bothrapid filling with the fluid and (in the event of risk of frost) rapidemptying of the heat exchanger assembly, due to the fluid being able toflow in and out through all of the pipelines 5 of the heat exchangerassembly simultaneously and in the same flow direction during bothfilling and outflowing.

FIGS. 4 and 5 show another exemplary embodiment of a heat exchangerassembly according to the invention, wherein the represented heatexchanger assembly contains two 2-pass heat exchangers which arearranged in a V-shape opposite each other and are inclined obliquely tothe vertical. The inclination of the heat exchangers with respect to thevertical plane is conveniently in an angular range from 15° to 70° andpreferably from 30° to 45°.

The structure of the heat exchanger arranged on the right-hand side ofFIG. 4 is explained below. The opposite heat exchanger arranged on theleft-hand side of the heat exchanger assembly is constructed similarly.The two 2-pass heat exchangers each comprise a first distributor 1,which is formed as an inlet distributor, a second distributor 2, whichis formed as an outlet distributor, and a (single) first deflectiondistributor 4, and a plurality of pipelines 5. The first distributor 1and the second distributor 2 are thereby arranged at the front face endA of the heat exchanger assembly. The deflection distributor 4 isarranged at the opposite end B of the heat exchanger assembly, i.e., atthe rear face. The pipelines 5 extend in a longitudinal direction L ofthe heat exchanger assembly from one end A to the opposite end B. Thepipelines 5 are thereby divided into a first group of pipelines 5 a anda second group of pipelines 5 b, wherein the first group of pipelines 5a serve as supply lines and the second group of pipelines 5 b serve asrecirculating lines. The pipelines 5 of the first group of pipelines 5 a(supply lines) connect the first distributor 1 (inlet distributor) withthe deflection distributor 4, the pipelines 5 of the second group ofpipelines 5 b (recirculating lines) connect the deflection distributor 4with the second distributor 2 (outlet distributor), as shown in FIG. 4.The pipelines 5 of the supply and recirculating lines run at leastpartially parallel to one another and are slightly inclined to thehorizontal, as can be seen in FIG. 6c . The angle of inclination of thepipelines 5 to the horizontal is again preferably between 0.5° and 5°,particularly preferably between 2° and 4°, and in a preferred exemplaryembodiment the angle between the pipelines and the horizontal plane is3°.

A first connection piece 1 a is arranged on the first distributor 1(inlet distributor) at a lowest point T of this distributor 1. A secondconnection piece 2 a is also arranged at a corresponding location, i.e.,at a lowest point T, on the second distributor 2 (outlet distributor).On the second distributor 2 (outlet distributor), an additionalconnection piece, referred to as the third connection piece 3, isarranged at a highest point H. The deflection distributor 4 arranged atthe opposite end B of the heat exchanger assembly has a vent opening 10at a highest point H, into which a valve 11 is inserted, as shown inFIG. 5. The vent opening 10 can be opened or closed via this valve 11,wherein the valve 11 is conveniently formed as a self closing valvewhich closes automatically as soon as a fluid enters the valve. Amanually operated inspection valve 26 is provided below the valve 11,with which the upper end of the deflection distributor can be closed forinspection and maintenance work.

At least in the second connection piece 2 a, which is arranged at thelower end of the second distributor 2 (outlet distributor), acontrollable valve V (not shown here) is inserted for opening andclosing the second connection piece 2 a. Alternatively, the valve V canalso be placed at another location, e.g., in a fluid line connected tothe second connection piece 2 a.

In FIG. 6, an overview of the second exemplary embodiment of the heatexchanger assembly according to the invention schematically shows thefront face of the 2-pass heat exchanger assembly (FIG. 6a ), the rearface (FIG. 6b ) and a side view (FIG. 6c ), FIG. 6 shows in particularthe placement of the connection pieces 1 a, 2 a and 3 on the first andsecond distributors 1, 2 as well as the inclination of the pipelines 5towards the front end A.

In FIGS. 7 and 8, different operating modes of the second exemplaryembodiment of the heat exchanger assembly according to the invention(like FIGS. 4 to 6) are schematically shown. In the recooling mode shownin FIGS. 7a and 8a , water is conducted through the pipelines 5 (supplylines 5 a and recirculating lines 5 b) of the heat exchanger assembly asthe heat transfer medium. At the same time, cold air is sucked in fromthe environment by at least one fan 12 arranged on the upper side of theheat exchanger assembly (as shown in FIG. 6c ) and conducted through theheat exchangers of the heat exchanger assembly to perform a heatexchange between the heat transfer medium (water) conducted through thepipelines 5 and the drawn-in air. To increase heat transfer efficiency,fins 22 are in turn attached to the pipelines 5 (FIG. 8) in order toincrease the effective heat transfer area. Instead of conventionalfinned or fin-tube heat exchangers, micro-channel heat exchangers mayalso be used in this exemplary embodiment of the heat exchanger assemblyaccording to the invention.

In the recooling mode shown in FIGS. 7a and 8a , the fluid used as theheat transfer medium is introduced into the first distributor 1 (inletdistributor) via the first connection piece 1 a and is conducted fromthere through the pipelines 5 of the first group of pipelines 5 a(supply lines) to the deflection distributor 4 and deflected thereininto the pipelines of the second group of pipelines 5 a (recirculatinglines). The fluid flows through the recirculating lines back into thesecond distributor 2 (outlet distributor). The fluid is withdrawn fromthe outlet distributor 2 through the third connection piece 3 arrangedat the top end of the outlet distributor 2 and directed as a coolingmedium into a cooling-medium reservoir (tank B) or directly to aconsumer to be cooled, via a fluid line connected to the thirdconnection piece 3.

In the recooling mode according to FIGS. 7a and 8a , the secondconnection piece 2 a is closed by the valve V arranged therein.

In FIGS. 7b and 8b , the heat exchanger assembly is shown in each casein a filling mode, in which the heat exchanger can either be filled forthe first time or can be refilled with the fluid after emptying. Infilling mode, the lower connection pieces 1 a, 2 a (first and secondconnection pieces), which are arranged at the lower end of the first andsecond distributors 2, respectively, are open. As a result, the fluidcan be simultaneously filled into the first and second distributors 1, 2via the lower connection pieces 1 a, 2 a. The fluid then flows, as shownin FIGS. 7b and 8b , simultaneously through all of the pipelines 5(i.e., through both the supply lines 5 a and the recirculating lines 5b) in the same direction of flow from the one end A of the heatexchanger assembly to the opposite end B. Due to the inclination of thepipelines 5 towards the front end A, the fluid in the pipelines 5thereby flows upwards against gravity in the direction of the deflectiondistributor 4 arranged at the rear face end B. The air present in thedeflection distributor 4 is forced out through the vent openings 10 atthe upper end of the deflection distributor, whereby the deflectiondistributor 4 is vented. In order to prevent the fluid from escapingfrom the vent opening on the deflection distributor 4 when the heatexchangers are completely filled with the filled fluid, a self closingvalve 11 is conveniently arranged in the vent opening 10.

Conversely, analogously to the filling of the heat exchanger assemblywith the fluid, the heat exchanger assembly can also be rapidly emptiedby opening the valve V in or on the second connection piece 2 a. FIGS.7c and 8c each show an emptying mode of the heat exchanger assembly inwhich, with open valve V in the second connection piece 2 a, the fluidcan flow simultaneously from all of the pipelines 5 (i.e., from both thesupply lines 5 a and the recirculating lines 5 b) by gravity and in thesame flow direction along the incline of the pipelines 5 from the rearend B to the front end A into the first and second distributors 1, 2. Inthis case, the flow of the fluid is again facilitated by the inclinationof the pipelines 5 towards the front end A and by the ventilation of thedeflection distributor 4 via the vent opening 10. Finally, the fluid canflow out through the lower connection pieces 1 a, 2 a (first and secondconnection pieces) into a fluid line (not shown here) connected to saidconnection pieces 1 a, 2 a.

By way of example, FIG. 9 shows a cooling system in which a heatexchanger assembly according to the invention may be used. The coolingsystem shown schematically in FIG. 9 comprises a circuit K in which afluid, in particular water, is conducted as a heat transfer medium, atank B which is connected to the circuit K and in which the fluid isstored, a heat source Q which supplies heat to the fluid at the locationof the heat source, and at least one heat exchanger assembly accordingto the invention which is used in the cooling system as a recooler R inorder to cool the fluid by heat exchange with the ambient air. In theexample shown in FIG. 9, the heat exchanger assembly having two 2-passheat exchangers as shown in FIGS. 4 to 6 is used as the recooler R.

In the process, the recooler R of the cooling system shown in FIG. 9 isconnected to the tank B via fluid lines 9. The tank B is preferably opento the surroundings of the tank location. A fluid line 19 leads from thetank B to the heat source Q in order to supply the cooled fluid storedin tank B as the cooling medium to the heat source Q. A first pump P1 isprovided for delivering the fluid from the tank B to the heat source Q.At the location of the heat source Q, the fluid is heated by heatexchange and fed back to the recooler R through another line 29.Conveniently, a second pump P2 is arranged in the line 29, whichdelivers the fluid from the heat source Q back to the recooler R. Abranch line 30 branches off from the line 29 into the tank B. A valve V4is provided for opening and closing the branch line 30. Another valve V3is arranged downstream of the branch line 30 in the line 29. The line 29branches at a branch point Z into a recirculating line 31 to the tank Band into a feed line 32 leading to the recooler R. Another valve V2 isarranged in the recirculating line 31 for opening and closing this line.The feed line 32 branches into a central feed line and two secondarylines, in each of which a three-way valve V1 is arranged. The centralfeed line branches again into two branches, wherein a first branch is inconnection with the first connection piece 1 a of the left heatexchanger and a second branch is in connection with the first connectionpiece 1 a of the right heat exchanger. The secondary lines lead to thesecond connection piece 2 a of the left and right heat exchanger, as canbe seen in FIG. 9b . The feed line 32 is thus connected to the lowerconnection pieces 1 a and 2 a of the heat exchanger assembly via thethree-way valves V1. A discharge line 33 is connected to the (upper)third connection piece 3 of the heat exchanger assembly, which leads toline 9 and is connected to it.

FIG. 10 shows various operating modes of the heat exchanger assembly inthe cooling system of FIG. 9. The fluid is represented by a dashed linewhen in a warm state and represented by a solid line when in a coldstate. Where the line is dotted, there is no flow of fluid.

FIG. 10a shows the cooling system from FIG. 9 in recooling mode. In thiscase, valves V2 and V4 are closed so that lines 30 and 31 are closed.Valve V3 is open so that the fluid heated by heat source Q can flowthrough lines 29 and 32 to the recooler R. In this case, the three-wayvalves V1 are closed so that the fluid can flow from line 32respectively to the first connection piece 1 a of the first distributor1 (inlet distributor) of the two multi-pass heat exchangers and therebyenter the heat exchanger assembly. After the fluid has passed throughthe multi-pass heat exchangers of the recooler R several times, thecooled fluid exits the recooler R at the third connection piece 3 andflows, through the line 33 connected to the third connection piece 3, tothe line 9 and from there into tank B in which the cooled fluid isstored.

In the emptying mode shown in FIG. 10b , valves V2 and V4 are open andvalve V3 is closed. The three-way valves V1 are switched so that thefluid can flow from the lower connection pieces 1 a, 2 a (first andsecond connection pieces) into the fluid line 9 connected to theseconnection pieces and from there directly into tank B. During emptyingof the recooler R, the fluid heated by the heat source Q is returned totank B via the branch line 30 when valve V4 is open, without the fluidbeing directed through recooler R.

In the filling mode shown in FIG. 10 c, the valves V2 and V4 are closedand valve V3 is open. The three-way valves V1 are controlled in such away that the fluid heated by the heat source Q is conducted via thelines 29 and 32 to the lower connection pieces 1 a, 2 a (first andsecond connection pieces) of the multi-pass heat exchangers and entersthe recooler R from there. After the heat exchangers of recooler R havebeen completely filled, the recooler is switched to recooling mode (FIG.10a ).

FIG. 11 shows an exemplary embodiment of a cooling system in which twoheat exchanger assemblies according to the invention can be used asrecoolers R1, R2 in parallel or series mode. The two recoolers R1, R2can, for example, be used simultaneously in series for cooling the fluidused as the heat transfer medium in the cooling system. When the tworecoolers R1, R2 are used simultaneously, a maximum cooling capacity ofthe cooling system is achieved. If a lower cooling capacity is requiredto sufficiently cool the fluid, one of the two recoolers R1 or R2 can beturned off by the control device S of the cooling system.

In series mode, in which both recoolers R1, R2 are operatedsimultaneously to cool the fluid, valves V2 and V4 are closed and valveV3 is open so that the fluid heated by heat source Q can be introducedinto both recoolers R1, R2 respectively through first connection piece 1a. The fluid cooled in the recoolers R1, R2 exits the recoolers R1, R2at the third connection piece 3 in each case and flows through the fluidline 9 connected to the third connection piece 2 a into the tank B (asshown in FIG. 11).

In the operating mode of the cooling system of FIG. 11 shown in FIG. 12a, valves V3 and V4 are closed and valve V2 is open. As a result, onlythe second recooler R2 is operated in recooling mode. The first recoolerR1 is in a standby mode, in which no fluid is conducted through thepipelines of the first recooler R1.

In the operating mode shown in FIG. 12b , with valve V3 open and valvesV2 and V4 closed, the second recooler R2 is operated in recooling mode,in which the fluid heated by the heat source Q is introduced via thefirst connection piece 1 a into the heat exchangers of the secondrecooler R2, where it is cooled, and is ultimately directed out of thesecond recooler R2 through the second connection piece 2 a via the fluidline 9 connected to the third connection piece 3 and conducted into tankB. At the same time, the first recooler R1 is operated in filling mode,in which the fluid is simultaneously introduced into all of thepipelines 5 of the first recooler R1 via the first connection piece 1 aand the second connection piece 2 a of the heat exchangers in order tocompletely fill the recooler R1 with fluid.

To control the heat exchanger assembly according to the invention in thevarious operating modes, conveniently a plurality of sensors S1, S2 isused, with which ambient parameters, such as outside temperature (T_(U))and/or wind speed (v) can be detected and transferred to a controldevice S for processing. In addition to the ambient parameters, theinlet temperature (_(in)) of the fluid entering the heat exchangerassembly, the temperature of the fluid in the deflection distributors 4,6, and the (hydrostatic) pressure (p) and/or the flow rate of the fluidentering the inlet distributor 1 are conveniently detected viaadditional sensors T1, T2, P.

The control device which is denoted by reference sign S in the diagramof the cooling system in FIG. 9a is coupled to the valves V, V1, V2, V3,V4 in order to control them. The measured values detected by the sensorsS1, S2; T1, T2, P are transferred to the control device, and the controldevice calculates an output temperature (T_(out)) of the fluid as itexits the heat exchanger assembly based on the detected measured values.The calculation of the value of the outlet temperature (T_(out)) alsotakes into account the parameters of the heat exchanger assembly, inparticular its thermal capacity, the dimensioning of the heatexchangers, the number of passes of the fluid through the pipelines, thefluid used as the heat transfer medium and the volume flow rate of thefluid through the pipelines, in order to determine a (maximum) coolingof the fluid when emptying the heat exchanger assembly.

The control device controls the valves of the heat exchanger assembly sothat the heat exchanger assembly is operated in recooling mode as longas the calculated outlet temperature (T_(out)) is greater than or equalto a predetermined limit value (T_(min)). As soon as the calculatedoutput temperature (T_(out)) falls below the limit value (i.e., whenT_(out)>T_(min)), the heat exchanger assembly is switched to emptyingmode. This is done, for example, by electrically or pneumaticallyactuating the valves V, V1, V2, V3, V4.

The predetermined limit value (T_(min)) is conveniently above thefreezing point of the fluid used as the heat transfer medium by a valueΔ (i.e., above 0° C. for water), wherein the value Δ represents a safetydistance from the freezing point. Therefore, even in the event of rapidemptying, it is ensured that the fluid does not freeze if there is arisk of frost.

Preferably, the value Δ (and thus, when water is used as the heattransfer medium, the limit value T_(min)=0° C.+Δ) is between 2° C. and7° C.

Once the heat exchanger assembly has been completely emptied, it is leftin a standby mode, in which the heat exchangers are not filled withfluid. In standby mode, it is monitored whether the risk of frost haspassed or is ongoing by calculating the predicted output temperature(T_(out)) based on the detected ambient parameters and comparing it withthe limit value. Once the calculated outlet temperature (T_(out)) isgreater than or equal to the predetermined limit value (T_(min)), thecontrol device switches the heat exchanger assembly from standby modeinto filling mode. After the heat exchanger assembly has been completelyfilled, it is switched to recooling mode and operated until thecalculated outlet temperature (T_(out)) is below the limit value.

In the exemplary embodiment shown in FIG. 11, the heat exchangerassembly comprising a plurality of heat exchangers is controlled by thecontrol device in such a way that the individual multi-pass heatexchangers can be operated independently of one another in the variousoperating modes. In the process, the control device controls the numberof heat exchangers operated in recooling mode as a function of thedetected ambient parameters and/or the detected input temperature(T_(in)) of the fluid in order to be able to provide a required coolingcapacity. Expediently, the fluid volume conducted through the heatexchanger assembly per unit of time remains the same regardless of thenumber of heat exchangers operated in recooling mode. In the process,the control device monitors whether the temperature of the fluid cooledin the heat exchanger assembly and stored in the tank is within apreferred temperature range between a minimum and a maximum temperature.The preferred temperature range may be, for example, between 15° C. and22° C.

1. Heat exchanger assembly having at least one multi-pass heat exchanger, which comprises a first distributor having a first connection piece for connecting to a fluid line, a second distributor having a second connection piece for connecting to a fluid line, and at least one first deflection distributor, as well as a plurality of pipelines through which a fluid can flow, wherein the first distributor and the second distributor are arranged at one end of the heat exchanger assembly and the deflection distributor is arranged at an opposite end thereof, and the pipelines extend from the one end to the opposite end, and wherein the first connection piece is arranged at a lowest point or at least near the lowest point (of the first distributor and the second connection piece is arranged at a lowest point or at least near the lowest point of the second distributor, wherein a third connection piece is arranged on the first distributor and/or on the second distributor at a highest point or at least near the highest point thereof and at least one vent opening for pressure equalization with the environment is arranged at a highest point or at least near the-highest point of the deflection distributor.
 2. Heat exchanger assembly according to claim 1, wherein a first group of the plurality of pipelines are formed as supply lines and are connected to the first distributor and to the deflection distributor, and a second group of the plurality of pipelines are formed as recirculating lines and are connected to the second distributor and to the deflection distributor.
 3. Heat exchanger assembly according to claim 1, wherein the first distributor, the second distributor and the deflection distributor are each formed as a tubular manifold arranged such that a longitudinal axis thereof is vertical or oblique to a vertical axis thereof.
 4. Heat exchanger assembly according to claim 1, wherein the first distributor and the second distributor are arranged at a face end of the heat exchanger assembly, and wherein the deflection distributor arranged at an opposite face of the heat exchanger assembly.
 5. Heat exchanger assembly according to claim 1, wherein a controllable valve is arranged in the first connection piece and/or in the second connection piece.
 6. Heat exchanger assembly according to claim 1, wherein the heat exchanger has an external inflow surface which can be flowed against by a gas stream, and wherein the distributor which faces the inflow surface, contains the third connection piece.
 7. Heat exchanger assembly according to claim 1, wherein the plurality of pipelines are parallel to each other and obliquely to the horizontal, wherein an angle which the pipelines define with the horizontal is between 0.5° and 5°.
 8. Heat exchanger assembly according to claim 1, wherein in an emptying mode the fluid flows by gravity from each of the plurality of pipelines into one or more of the first distributor and the second distributor, and in that in a tilling mode the fluid flows against gravity from the first distributor and the second distributor into one or more of the plurality of pipelines.
 9. Heat exchanger assembly according to claim 2, wherein in a recooling mode the fluid flows into the supply lines through the first connection piece and flows out of the recirculating lines through the third connection piece.
 10. Heat exchanger assembly according to claim 8, wherein in emptying mode the fluid flows out by gravity via the first connection piece of the first distributor and the second connection piece of the second distributor into a lower fluid line which is connected to the first and second connection pieces.
 11. Heat exchanger assembly according to any preceding claim, characterized by a plurality of sensors for detecting ambient parameters, in particular outside temperature and/or wind speed.
 12. Heat exchanger assembly according to claim 1, wherein at least a part of the plurality of pipelines is adapted to be cranked towards the deflection distributor at its end facing the deflection distributor.
 13. Heat exchanger assembly according to claim 12, wherein the deflection distributor (4) is tubular in form and is arranged such that its longitudinal axis is inclined to the vertical, preferably by an angle in the range of 15° to 70° and in particular by an angle in the range of 15° to 45°.
 14. Heat exchanger assembly according to claim 1, wherein the heat exchanger assembly comprises two heat exchangers arranged opposite each other, each of which is inclined to the vertical and arranged in a V-shape relative to one another.
 15. Heat exchanger assembly according to any preceding claim, wherein the fluid passes through the pipelines (5) of each heat exchanger twice or four times.
 16. Heat exchanger assembly according to claim 1, further comprising a second deflection distributor and a third deflection distributor, wherein one of the deflection distributors is arranged at the end of the heat exchanger where the first and second distributors are located.
 17. Heat exchanger assembly according to claim 1, further comprising a valve having a predetermined maximum flow cross-section for the passage of air arranged in the vent opening, wherein the valve can he opened and closed and, when the valve is fully opened, a maximum flow cross-section for the passage of air is released and the valve closes automatically when the fluid enters the valve.
 18. Heat exchanger assembly according to any preceding claim, characterized by a control device for controlling the heat exchanger assembly, wherein the heat exchanger assembly can be operated in a recooling mode, an emptying mode or a filling mode via the control device as a function of ambient parameters, in particular outside temperature and/or wind speed.
 19. Cooling system comprising a circuit in which water is conducted as a heat transfer medium, a tank which is connected to the circuit and in which the water is stored, a heat source which supplies heat to the fluid at the location of the heat source, and a recooler in which the water is cooled by heat exchange with the ambient air, wherein the recooler contains at least one heat exchanger assembly according to claim 1,
 20. Method for operating a heat exchanger assembly having at least one heat exchanger, which comprises a first distributor (1) having a first connection piece (1 a) for connecting to a fluid line (9), a second distributor (2) having a second connection piece (2 a) for connecting to a fluid line (9), and at least one first deflection distributor (4), as well as a plurality of pipelines (5) through which a fluid, in particular water, can flow, wherein the first distributor (1) and the second distributor (2) are arranged at one end (A) of the heat exchanger assembly and the deflection distributor (4) is arranged at the opposite end (B) and the pipelines (5) extend from the one end (A) to the opposite end (B) and wherein the first connection piece (1 a) is arranged at a lowest point (T) or at least near the lowest point (T) of the first distributor (1) and the second connection piece (2 a) is arranged at a lowest point (1) or at least near the lowest point (T) of the second distributor (2), and the heat exchanger assembly, depending on ambient parameters, in particular the outside temperature, is alternately operated in different operating modes, comprising a recooling mode, an emptying mode, a filling mode and a standby mode, characterized in that in the emptying mode the fluid flows by gravity out of all of the pipelines (5) into the first distributor (1) and the second distributor (2) and from there in each case via the first and the second connection piece (1 a, 2 a) into a fluid line (9), and in that in the filling mode the fluid flows against gravity Out of the first distributor (1) and the second. distributor (2) into all of the pipelines (5).
 21. Method according to claim 20, characterized in that on the first distributor (1) and/or on the second distributor (2) a third connection piece (3) is arranged at a highest point (H) or at least near the highest point (H) of the respective distributor (1 or 2), and in that at least one vent opening (10) is arranged at a highest point (T) or at least near the highest point (T) of the deflection distributor (4) for pressure equalization with the environment, wherein
 22. Method according to claim 21, characterized in that the fluid in the recooling mode is introduced into the heat exchanger assembly via the first connection piece (la) at the lowest point (T) or at least near the lowest point (T) of the first distributor (I) and is discharged via the third connection piece (3) at the highest point (H) or at least near the highest point (H) of the second distributor (2),
 23. Method according to any of claims 20 to 22, characterized in that the heat exchanger assembly is operated in standby after the emptying mode, in which the pipelines (5) are at least substantially empty.
 24. Method according to any of claims 20 to 23, characterized in that the switching of the operating modes of the heat exchanger assembly is performed by actuation, in particular opening and closing, of valves of the heat exchanger assembly.
 25. Method according to claim 24, characterized in that the switching of the operating modes is perforated by electrically controlling the valves.
 26. Method according to any of claims 20 to 25, characterized in that ambient parameters, in particular outside temperature (T_(U)) and/or wind speed (v), as well as the inlet temperature (T_(in)) of the fluid on entering the heat exchanger assembly are detected by means of sensors and transferred as measured values to a control device, and in that the control device calculates an outlet temperature (T_(out)) of the fluid as it exits the heat exchanger assembly based on the detected measured values.
 27. Method according to claim 26, characterized in that the control device operates the heat exchanger assembly in recooling mode as long as the calculated outlet temperature (T_(min)) is greater than or equal to a predetermined limit value (T_(min)) and switches the heat exchanger assembly to emptying mode when the calculated outlet temperature (T_(out)) is below the limit value (T_(min)).
 28. Method according to any of claim 26 or 27, characterized in that the control device switches the heat exchanger assembly from standby to filling mode as soon as the calculated outlet temperature (T_(out)) is greater than or equal to a predetermined limit value (T_(min)).
 29. Method according to any of claims 26 to 28, characterized in that the predetermined limit value (T_(min)) is greater than 0° C. and is preferably in the range of 1° C. to 7° C.
 30. Method according to any of claims 26 to 29, characterized in that the predefined limit value (T_(min)) is determined as a function of the thermal capacity of the heat exchanger assembly and in particular as a function of the dimensioning, the number of passes of the fluid through the pipelines the fluid used and the volume flow rate of the fluid through the pipelines.
 31. Method according to one of the methods according to any of claims 26 to 30, characterized in that the heat exchanger assembly comprises a plurality of heat exchangers which are each controlled by the control device and can be operated independently of one another in the various operating modes, wherein the control device controls the number of heat exchangers operated in recooling mode as a function of the detected ambient parameters and; the detected inlet temperature (T_(in)) of the fluid.
 32. Method according to claim 31, characterized in that the fluid volume conducted through the heat exchanger assembly per unit of time remains the same regardless of the number of heat exchangers operated in. recooling mode. 